Teratoma in the cerebrum of a fantail pigeon

This is the first report of a primary teratoma in the cerebral cortex of a 1-year-old fantail pigeon and one of the few reports of intracranial teratomas in birds. The clinical signs were sudden onset of listlessness and a head tilt to the right. The right cerebral hemisphere contained an unencapsulated teratoma that included adipose, cartilaginous, fibrous and undifferentiated mesenchymal tissue as well as keratinized and glandular epithelial structures. Immunohistochemistry designed for mammals proved very useful and has been used to investigate the two germ cell lines, epithelial and mesenchymal, detected in the neoplasm. Indirect immunohistochemistry testing using vimentin, pancytokeratin, smooth muscle actin, neuron-specific enolase, and S-100 was done. Vimentin, smooth muscle actin and pancytokeratin immunoreactivity was strong. Neuron-specific enolase immunoreactivity was strongly positive in the normal brain adjacent to the neoplasm but there was no immunoreactivity within the neoplasm. Also, there was no S-100 immunoreactivity, suggesting that the mammalian proteins on which the immunohistochemistry is based are not present in pigeons.